Hi David and others,
I really wonder what the performance difference would be between David's
original:
for $r in cts:search(doc("/RxNorm/rxnsat.xml")/rxnsat/row,
cts:element-query( xs:QName("RXAUI") , $id2 ))
return $r
And these:
for $r in cts:search(
doc("/RxNorm/rxnsat.xml")/rxnsat/row,
cts:element-value-query( xs:QName("RXAUI") , $id2 )
)
return $r
for $r in cts:search(
/rxnsat/row,
cts:and-query((
cts:element-value-query( xs:QName("RXAUI") , $id2 ),
cts:document-query("/RxNorm/rxnsat.xml")
))
)
return $r
And
for $r in cts:search(
//row,
cts:and-query((
cts:element-value-query( xs:QName("RXAUI") , $id2 ),
cts:document-query("/RxNorm/rxnsat.xml")
))
)
where parent::rxnsat
return $r
David, is it really only the for loop that takes 5 sec? Or are you doing more
in the same query? A cts:search taking 5 sec doesn't sound as a cts:search that
is only relying on indexes, there must be something else going on, I am sure..
Kind regards,
Geert
>
Drs. G.P.H. Josten
Consultant
http://www.daidalos.nl/
Daidalos BV
Source of Innovation
Hoekeindsehof 1-4
2665 JZ Bleiswijk
Tel.: +31 (0) 10 850 1200
Fax: +31 (0) 10 850 1199
http://www.daidalos.nl/
KvK 27164984
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> From: [email protected]
> [mailto:[email protected]] On Behalf Of
> Lee, David
> Sent: zaterdag 5 december 2009 15:20
> To: [email protected]
> Subject: [MarkLogic Dev General] Interesting case where ML
> refuses to optimize XPath
>
> I have 2 xml docs, each about 1GB and about 2 mil fragments
> ("rows") each ... in fact the elements are called "rows".
>
> Each "row" element is about 500 bytes. But I dont yet have
> a better way to fragment them.
>
> ( Yes Its been suggested to split these to seperate docs and
> I may experiment with that. )
>
>
>
> Here's a case where I've found ML refuses to optimize xpaths.
>
>
>
> First off, this expression takes about 5 seconds, which I
> find a little slow ... it returns 8 rows.
>
>
>
>
>
> declare variable $id := '2483417';
>
> for $r in doc("/RxNorm/rxnsat.xml")/rxnsat/row[RXAUI eq $id]
>
> return $r
>
>
>
>
>
> Now to complicate things I actually need $id from a previous
> query so the real query is like
>
>
>
>
>
> declare variable $id := '2483417';
>
> declare variable $c :=
> doc("/RxNorm/rxnconso.xml")/rxnconso/row[RXAUI eq $id];
>
> declare variable $id2 as xs:string := $c/RXAUI/string();
>
>
>
> for $r in doc("/RxNorm/rxnsat.xml")/rxnsat/row[RXAUI eq $id2]
>
> return $r
>
>
>
> This takes about 1 minute ! .. Checking the profile I find
> the expression row[ RXAUI eq $id] is evaluated a million
> times ... indicating its not doing indexing.
>
>
>
> I've tried all sorts of combinations of these like
>
>
>
> doc("/RxNorm/rxnsat.xml")/rxnsat/row[xs:string(RXAUI) eq $id2]
>
> doc("/RxNorm/rxnsat.xml")/rxnsat/row[RXAUI eq $c/RXAUI]
>
> doc("/RxNorm/rxnsat.xml")/rxnsat/row/RXAUI[. eq $id2]/ancestor::row
>
>
>
>
>
> All to the same avail ... no indexing !
>
>
>
> But of course this brings things back to speed
>
>
>
> ---------
>
> for $r in cts:search(doc("/RxNorm/rxnsat.xml")/rxnsat/row,
>
> cts:element-query( xs:QName("RXAUI") , $id2 ))
>
> return $r
>
>
>
> ------------
>
>
>
>
>
> Still takes too long (about 5 sec) ... but its back to
> realtime atleast.
>
>
>
> I'm experimenting now with fields ...
>
>
>
> But I find it strange that I cant the xpath expression to use
> the indexes in one case but it does in another that seems
> almost identical to me.
>
>
>
> This expression
>
> declare variable $id2 as xs:string := $c/RXAUI/string();
>
>
>
> should tell the system that $id2 is a single string so why
> wont it use it in xpath based index queries ?
>
>
>
>
>
>
>
>
>
> ----------------------------------------
>
> David A. Lee
>
> Senior Principal Software Engineer
>
> Epocrates, Inc.
>
> [email protected] <mailto:[email protected]>
>
> 812-482-5224
>
>
>
>
>
>
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